A multi-stage treatment system for formaldehyde-containing wastewater

Abstract

This invention relates to the field of multi-stage treatment technology for formaldehyde-containing wastewater, and discloses a multi-stage treatment system for formaldehyde-containing wastewater, including a primary sedimentation tank and a reaction tank placed in parallel. Square holes are provided at the bottom of both ends of the primary sedimentation tank and the reaction tank. The system also includes a heating plate, which is inclinedly arranged in the primary sedimentation tank and the reaction tank to heat the water overflowing from the primary sedimentation tank and guide it into the reaction tank. An overflow port is provided at the front of the primary sedimentation tank. Through the setting of a transfer device, the formaldehyde-containing wastewater is first introduced into the primary sedimentation tank for preliminary sedimentation. Then, through overflow, it is heated on the heating plate and guided into the reaction tank. Potassium permanganate solution and a large amount of lime powder are added. The excess lime powder accelerates the reaction efficiency. After a period of time in the reaction tank, the excess lime powder, along with the precipitate, falls through the square holes into the transfer device, which then transports it into the primary sedimentation tank.

Description

Technical Field

[0001] This invention relates to the field of multi-stage treatment technology for formaldehyde-containing wastewater, specifically a multi-stage treatment system for formaldehyde-containing wastewater. Background Technology

[0002] Formaldehyde, as an important organic chemical raw material, is widely used in various industrial fields such as the production of artificial boards, coatings, textile printing and dyeing, pharmaceutical synthesis, and resin manufacturing due to its excellent anti-corrosion, adhesive, and cross-linking properties. However, in these production processes, formaldehyde can enter the wastewater system in large quantities due to incomplete reaction, product washing, or equipment cleaning, forming formaldehyde-containing industrial wastewater. Formaldehyde-containing wastewater has significant pollution hazards, but the current equipment used to treat formaldehyde-containing wastewater has the following shortcomings:

[0003] In the treatment of formaldehyde-containing wastewater, the initial formaldehyde concentration is extremely high, accompanied by suspended particles, high salt content, and recalcitrant organic matter. To reduce the formaldehyde concentration to a tolerable range for subsequent processes (especially biological treatment), pretreatment of the high-concentration formaldehyde-containing wastewater is necessary. Currently, the pretreatment process typically utilizes sedimentation, placing the wastewater in a sedimentation tank for settling, followed by overflow to separate particulate matter. Similarly, when reducing formaldehyde concentration, potassium permanganate solution and lime are added to the reaction tank in a certain ratio. To maximize formaldehyde removal efficiency, excessive lime is often added to quickly adjust the pH of the wastewater. However, after the reaction reaches equilibrium, the excess lime mixes with the precipitate under gravity, sinking to the bottom and forming scale. This results in low reuse rates of the remaining lime and increases the treatment cost of the formaldehyde-containing wastewater. Therefore, a system that can rapidly pretreat formaldehyde-containing wastewater is urgently needed. Summary of the Invention

[0004] This invention provides a multi-stage treatment system for formaldehyde-containing wastewater, which has the advantages of making full use of resources and accelerating the formaldehyde removal rate in wastewater, thus solving the problems mentioned in the background art.

[0005] This invention provides the following technical solution: a multi-stage treatment system for formaldehyde-containing wastewater, comprising a primary sedimentation tank and a reaction tank placed in parallel, with square holes at both ends of the primary sedimentation tank and the reaction tank. The system also includes: a heating plate, which is inclinedly disposed in the primary sedimentation tank and the reaction tank, capable of heating the water overflowing from the primary sedimentation tank and guiding it into the reaction tank; an overflow outlet is provided on the front side of the primary sedimentation tank, and an inlet is provided on the rear side of the reaction tank; wastewater flows out from the overflow outlet, passes through the heating plate, and then flows into the reaction tank from the inlet; and a material transfer device, movably disposed at the ends of the primary sedimentation tank and the heating plate, capable of rotating to guide excess lime mixture inside the reaction tank below the square holes in the primary sedimentation tank for reuse, and to remove precipitated waste from the primary sedimentation tank.

[0006] Preferably, the material transfer device includes a rotating base plate and a rotating motor. The rotating motor is located at the bottom center of the rotating base plate, and its rotating shaft is fixedly connected to the rotating base plate. Transfer boxes that fit square holes are evenly fixed on the rotating base plate, and a three-way solenoid valve is provided at one end of the transfer box. The transfer box has two cavities inside, and the middle partition is provided with a through hole. The three-way solenoid valve is connected to the lower cavity of the transfer box.

[0007] Preferably, a rack is fixedly installed on the top of the primary sedimentation tank, a filtration device is movably installed inside the primary sedimentation tank and the reaction tank, and a servo motor is installed on the top of one end of the filtration device. A drive shaft is movably installed on the filtration device, and a traveling gear that meshes with the rack is fixedly installed on the drive shaft. A belt drive device for transmission is provided between the drive shaft and the servo motor.

[0008] Preferably, the filtration device includes a T-shaped frame, with limiting frames movably arranged on both sides of the T-shaped frame, a filter cloth arranged on the top of the limiting frame, a square filter plate movably arranged on the limiting frame and fixedly connected to one end of the filter cloth, and a telescopic rod I movably arranged on the T-shaped frame, with the extended end of the telescopic rod I movably connected to the limiting frame for adjusting the angle of the limiting frame.

[0009] Preferably, the limiting frame includes a top limiting rod and a steering rod, the top limiting rod and the steering rod are movably connected, and the height of the steering rod is the same as the height of the square filter plate and the width of the square hole. The bottom of the T-shaped frame is provided with a telescopic rod II, and the protruding end of the top of the telescopic rod II is movably connected to the top of the steering rod.

[0010] Preferably, a rotating gear is fixedly installed on the rotating shaft of the filter cloth, a drive motor is fixedly installed on the top of the other end of the T-shaped frame, a transmission gear that meshes with the rotating gear is movably installed on the T-shaped frame, and a main gear that meshes with the transmission gear is fixedly installed on the output shaft of the drive motor.

[0011] Preferably, the filter device is internally provided with a flow guiding device, which includes a support frame and a connecting plate. Multiple flow guiding boxes are movably arranged on the support frame and connected in series by the connecting plate. A connecting rod is movably arranged on the top of the connecting plate, and a telescopic rod III is movably arranged on the top of the support frame. The extended end of the telescopic rod III is movably connected to the connecting rod. The telescopic rod III drives the flow guiding box to deflect in different directions by extending and retracting. An impeller is movably arranged inside the flow guiding box.

[0012] Preferably, an end filter box is fixedly installed at the end of the primary sedimentation tank and the reaction tank. The end filter box includes a fixed box, a receiving plate is fixedly installed on the top of the fixed box, and one end of the receiving plate is connected to one end of the primary sedimentation tank. A spiral filter plate is fixedly installed in the middle of the fixed box, and a connecting pipe is fixedly installed on the spiral filter plate, penetrating the bottom of the fixed box, so that the wastewater on the receiving plate can be guided into the transfer box below for rinsing.

[0013] Preferably, an ash collection box is fixedly installed on the filter device and above the heating plate, and a drive shaft passes through the ash collection box. An abutment rod that can abut against the bottom of the inner cavity of the ash collection box is fixedly installed on the drive shaft. Guide strips are uniformly fixedly installed on the upper surface of the heating plate.

[0014] The fixed box has two protective boxes fixedly installed inside, and the protective boxes have intercepting plates movably installed inside. The two intercepting plates are respectively movably engaged with the ends of the primary sedimentation tank and the reaction tank, and can be closed above the square holes. The protective boxes are symmetrically fixedly installed with telescopic rods IV, and the extended ends of the telescopic rods IV are fixedly connected to the side of the intercepting plates.

[0015] The present invention has the following beneficial effects:

[0016] By using a transfer device, formaldehyde-containing wastewater is first introduced into a primary sedimentation tank for initial settling. Then, it overflows, is heated on a heating plate, and guided into a reaction tank. Potassium permanganate solution and a large amount of lime powder are added, and the excess lime powder accelerates the reaction efficiency. After a period of time in the reaction tank, the excess lime powder, along with the sediment, falls through square holes into the transfer device. Under the transfer of the transfer device, it can be transported into the primary sedimentation tank. The high concentration of formaldehyde-containing wastewater consumes the lime powder. On the one hand, the excess lime powder in the reaction tank can be reused, reducing wastewater treatment costs. On the other hand, the excess lime in the primary sedimentation tank can be used to pre-treat the formaldehyde-containing wastewater, thereby shortening the treatment time in the reaction tank and improving wastewater treatment efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 This is a schematic diagram of the overall structure of the material transfer device of the present invention;

[0019] Figure 3 This is a partial cross-sectional schematic diagram of the material transfer device of the present invention;

[0020] Figure 4 This is a schematic diagram of the installation of the filter device and flow guiding device of the present invention;

[0021] Figure 5 This is a schematic diagram of the filter device structure of the present invention;

[0022] Figure 6 This is a schematic diagram of the unfolded filter cloth structure of the present invention;

[0023] Figure 7 This is a schematic diagram showing the installation and distribution of the transmission gears and rotating gears in the structure of this invention;

[0024] Figure 8 This is a schematic diagram of the flow guiding device of the present invention;

[0025] Figure 9 This is a schematic diagram of the square filter plate covering the square holes of the present invention;

[0026] Figure 10 This is a partial cross-sectional schematic diagram of the end filter box of the structure of the present invention.

[0027] Figure 11 This is a schematic diagram of the installation of the interceptor plate of the present invention.

[0028] In the diagram: 1. Primary sedimentation tank; 2. Reaction tank; 3. Heating plate; 4. Overflow outlet; 5. Inlet; 6. Transfer device; 61. Rotating base plate; 62. Transfer box; 63. Three-way solenoid valve; 64. Rotating motor; 7. Filtration device; 71. T-shaped frame; 72. Limiting frame; 721. Top limiting rod; 722. Steering rod; 73. Filter cloth; 74. Square filter plate; 75. Telescopic rod I; 76. Telescopic rod II; 77. Rotating gear; 78. Drive motor; 79. Transmission gear; 8 81. Flow guiding device; 82. Support frame; 83. Flow guiding box; 84. Connecting plate; 85. Connecting rod; 86. Telescopic rod III; 9. Impeller; 10. End filter box; 11. Fixed box; 12. Receiving plate; 13. Spiral filter plate; 14. Connecting pipe; 15. Ash collection box; 16. Rack; 17. Drive shaft; 18. Traveling gear; 19. Belt drive device; 10. Servo motor; 10. Abutment rod; 11. Flow guiding strip; 12. Protective box; 13. Interception plate; 24. Telescopic rod IV. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figure 1-11 A multi-stage treatment system for formaldehyde-containing wastewater includes a primary sedimentation tank 1 and a reaction tank 2 placed in parallel. Square holes are provided at the bottom of both ends of the primary sedimentation tank 1 and the reaction tank 2. The system also includes: a heating plate 3, which is inclinedly disposed in the primary sedimentation tank 1 and the reaction tank 2, to heat the water overflowing from the primary sedimentation tank 1 and guide it into the reaction tank 2; an overflow port 4 is provided on the front side of the primary sedimentation tank 1, and an inlet 5 is provided on the rear side of the reaction tank 2; wastewater flows out from the overflow port 4, passes through the heating plate 3, and then flows into the reaction tank 2 from the inlet 5; and a material transfer device 6, which is movably disposed at the ends of the primary sedimentation tank 1 and the heating plate 3, to guide excess lime mixture inside the reaction tank 2 below the square holes in the primary sedimentation tank 1 for reuse, and to remove the precipitated waste from the primary sedimentation tank 1.

[0031] Untreated formaldehyde-containing wastewater is injected into primary sedimentation tank 1 for initial settling. The wastewater then overflows from overflow port 4 and, guided and heated by heating plate 3, flows into reaction tank 2 at a certain temperature through inlet 5. During this process, lime powder and potassium permanganate solution are added to reaction tank 2 to eliminate formaldehyde in the wastewater. After a period of time, under gravity, some of the sediment in primary sedimentation tank 1 and reaction tank 2 falls through square holes into transfer device 6. After transfer device 6 rotates 90 degrees, the sediment in primary sedimentation tank 1 is discharged first. Subsequently, the transfer device 6 rotates 90 degrees again, which can send the precipitate in the reaction tank 2 into the direction hole below the primary sedimentation tank 1. Then, the transfer device 6 is connected to the impact water flow, which can flush the precipitate containing lime into the primary sedimentation tank 1. It can have a preliminary reaction with the formaldehyde-containing wastewater in the primary sedimentation tank 1, remove the lime in the precipitate, make full use of the excess lime put into the reaction tank 2, and avoid the lime remaining in the precipitate and being wasted. This not only ensures the formaldehyde removal efficiency of the wastewater in the reaction tank 2, but also makes full use of the excess lime, thereby reducing the cost of formaldehyde-containing wastewater treatment.

[0032] The transfer device 6 includes a rotating base plate 61 and a rotating motor 64. The rotating motor 64 is located at the bottom center of the rotating base plate 61, and its rotating shaft is fixedly connected to the rotating base plate 61. Transfer boxes 62 that fit square holes are evenly fixed on the rotating base plate 61, and a three-way solenoid valve 63 is provided at one end of the transfer box 62. The interior of the transfer box 62 is provided with two cavities, and the middle partition is provided with a through hole. The three-way solenoid valve 63 is connected to the lower cavity of the transfer box 62. When the precipitate in the primary sedimentation tank 1 and the reaction tank 2 is transferred from the primary sedimentation tank 1 to the reaction tank 2, the transfer device 64 is used to transfer the material from the primary sedimentation tank 61 to the reaction tank 62. The lime-containing precipitate from the square hole falls into the transfer box 62. Then, driven by the rotating motor 64, the lime-containing precipitate below the reaction tank 2 is transferred to the area below the square hole in the primary sedimentation tank 1. Subsequently, a wastewater injection pipe is connected to the upper pipe of the three-way solenoid valve 63, and the wastewater is injected into the transfer box 62 from the three-way solenoid valve 63. This carries the lime-containing precipitate in the transfer box 62 into the primary sedimentation tank 1, so that the lime-containing precipitate can be dispersed in the primary sedimentation tank 1 and come into contact with the wastewater, allowing for the secondary utilization of the lime in the precipitate.

[0033] A rack 11 is fixedly installed on the top of the primary sedimentation tank 1. A filter device 7 is movably installed inside the primary sedimentation tank 1 and the reaction tank 2. A servo motor 15 is installed on the top of one end of the filter device 7. A drive shaft 12 is movably installed on the filter device 7. A traveling gear 13 that meshes with the rack 11 is fixedly installed on the drive shaft 12. A belt drive device 14 for transmission is provided between the drive shaft 12 and the servo motor 15. Through the transmission of the servo motor 15 and the belt drive device 14, the drive shaft 12 is driven to rotate, and the drive shaft 12 drives the traveling gear. 13 moves on rack 11, thereby driving filter device 7 to move inside primary sedimentation tank 1 and reaction tank 2 respectively, so that filter device 7 can screen the impurities inside primary sedimentation tank 1 and reaction tank 2 and bring them above the square hole. Under the action of gravity, they can fall into transfer box 62, quickly concentrating impurities in wastewater for subsequent treatment. At the same time, it can also quickly filter impurities in wastewater, increase the cleanliness of wastewater, and prevent sediment from remaining in the tank for a long time, forming scale that adheres to the tank wall, which would increase the difficulty of subsequent cleaning.

[0034] The filtration device 7 includes a T-shaped frame 71, with limiting frames 72 movably mounted on both sides of the T-shaped frame 71. A filter cloth 73 is mounted on the top of the limiting frames 72. A square filter plate 74, fixedly connected to one end of the filter cloth 73, is movably mounted on the limiting frames 72. A telescopic rod I 75 is movably mounted on the T-shaped frame 71, with its extended end movably connected to the limiting frames 72 for adjusting the angle of the limiting frames 72. Under gravity, the filter cloth 73 is lowered via the square filter plate 74. The limiting frames 72 have grooves that effectively limit the movement of the filter cloth 73 and the square filter plate 74, preventing large gaps between the filter cloth 73 and the limiting frames 72, which could cause impurities to escape from the gaps. After descending, filter cloth 73 intercepts the cross-section of primary sedimentation tank 1. Subsequently, during the movement of filter device 7, it filters impurities in primary sedimentation tank 1, causing impurities to follow filter cloth 73 towards the edge of primary sedimentation tank 1. Meanwhile, after the wastewater is filtered by filter cloth 73 on one side, it impacts filter cloth 73 on the other side, thereby knocking down the impurities adhering to filter cloth 73 on the other side, effectively preventing large-area clogging of filter cloth 73. At the same time, telescopic rod I 75 can push the limiting frame 72 to tilt to one side, thereby causing filter cloth 73 to move in an inclined manner, which can not only increase the filtration area, but also better gather impurities under the oblique force, so that impurities can settle more quickly.

[0035] The limiting frame 72 includes a top limiting rod 721 and a turning rod 722. The top limiting rod 721 and the turning rod 722 are movably connected, and the height of the turning rod 722 is the same as the height of the square filter plate 74 and the width of the square hole. A telescopic rod II 76 is provided at the bottom of the T-shaped frame 71. The protruding end of the top of the telescopic rod II 76 is movably connected to the top of the turning rod 722. After the filter cloth 73 pushes the impurities to the edge of the primary sedimentation tank 1, after standing for a period of time, the telescopic rod II 76 pushes the turning rod 722 downward to cover the area above the square hole, so that the impurities can be quickly gathered into the transfer box 62 and stacked to increase the density of the impurities, so that a large number of impurities can be moved out with the rotation of the transfer device 6, thereby cleaning most of the solid impurities in the primary sedimentation tank 1 and the reaction tank 2.

[0036] A rotating gear 77 is fixedly installed on the rotating shaft of the filter cloth 73. A drive motor 78 is fixedly installed on the top of the other end of the T-shaped frame 71. A transmission gear 79 that meshes with the rotating gear 77 is movably installed on the T-shaped frame 71. A main gear that meshes with the transmission gear 79 is fixedly installed on the output shaft of the drive motor 78. Through the transmission of the main gear on the drive motor 78 and the transmission gear 79, the rotating gear 77 can be driven to rotate, thereby driving the filter cloth 73 to rotate. This realizes the automatic winding and unwinding of the filter cloth, preventing excessive cleaning of the lime in the reaction tank 2 during the reaction process, which would reduce the reaction efficiency. Only periodic unwinding is needed to filter impurities.

[0037] The filter device 7 has an internal flow guiding device 8, which includes a support frame 81 and a connecting plate 83. Multiple flow guiding boxes 82 are movably mounted on the support frame 81 and connected in series via the connecting plate 83. A connecting rod 84 is movably mounted on the top of the connecting plate 83, and a telescopic rod 85 is movably mounted on the top of the support frame 81. The extended end of the telescopic rod 85 is movably connected to the connecting rod 84. The extension and retraction of the telescopic rod 85 causes the flow guiding boxes 82 to deflect. An impeller 86 is movably mounted inside the flow guiding box 82. When the filter device 7 is in use and filtration is not required, the extension and retraction of the telescopic rod 85 pushes or pulls the connecting plate 83, thus guiding the flow. One end of the guide box 82 in the direction of movement can be deflected downwards, and the bottom guide box 82 contacts the bottom of the reaction tank 2. Therefore, during this process, as the filter device 7 moves, the wastewater in the reaction tank 2 passes through the guide box 82, thereby raising the water layer in front of the guide box 82 and also raising the sediment at the bottom. This allows the precipitated lime to be lifted again and react with the formaldehyde in the wastewater. The raised water flow also merges with the wastewater behind it, forming a collision, which enhances the contact effect of lime, potassium permanganate and formaldehyde in the wastewater and strengthens the ion collision effect. Furthermore, inside the guide box 82, the wastewater is agitated by the impeller 86, which further enhances the agitation effect of the wastewater and increases the reaction rate.

[0038] End filter boxes 9 are fixedly installed at the ends of the primary sedimentation tank 1 and the reaction tank 2. Each end filter box 9 includes a fixed box 91, with a receiving plate 92 fixedly installed on the top of the fixed box 91. One end of the receiving plate 92 is connected to one end of the primary sedimentation tank 1. A spiral filter plate 93 is fixedly installed in the middle of the fixed box 91. A connecting pipe 94 is fixedly installed on the spiral filter plate 93, penetrating the bottom of the fixed box 91, which guides the wastewater on the spiral filter plate 93 to the transfer box 62 below for rinsing. The end filter boxes 9 are installed at both ends of the primary sedimentation tank 1 so that a portion of the wastewater, during the movement of the end filter boxes 9, is propelled by the thrust... The suspended solids on the top of the primary sedimentation tank 1 are scraped off when the connecting pipe 94 is at the top of the filter device 7. The solids flow to the receiving plate 92 along with the wastewater and are filtered by the receiving plate 92, leaving the suspended solids on the receiving plate 92. The wastewater can fall onto the spiral filter plate 93 and then be guided by the connecting pipe 94 to the transfer box 62 below it. The impurities discharged from the primary sedimentation tank 1 are washed away and discharged from the lower pipe of the three-way solenoid valve 63. On the one hand, the suspended solids in the primary sedimentation tank 1 are cleaned, and on the other hand, the overflowing wastewater is used to wash the transfer box 62, which facilitates the discharge of impurities.

[0039] A dust collection box 10 is fixedly installed on the filter device 7 above the heating plate 3, and a drive shaft 12 passes through the dust collection box 10. An abutment rod 16, which can abut against the bottom of the inner cavity of the dust collection box 10, is fixedly installed on the drive shaft 12. Guide strips 17 are evenly fixedly installed on the upper surface of the heating plate 3. Dust collection holes are evenly distributed at the bottom of the dust collection box 10, and its interior is filled with lime powder. When the overflow port 4 moves, the rotation of the drive shaft 12 also drives the abutment rod 16 to rotate inside the dust collection box 10. During this rotation, the end of the abutment rod 16 can abut against the center of the bottom of the dust collection box 10. The contact causes elastic deformation at the bottom of the ash collection box 10. Therefore, after each deformation, the lime powder inside the ash collection box 10 can fall, preventing the lime powder from getting stuck in the ash discharge hole under the action of accumulation force. The rotation of the contact rod 16 improves the uniformity of lime powder falling, so that the lime falls evenly onto the heating plate 3 and can quickly combine with the flowing wastewater to produce a reaction, improve the uniformity of lime distribution, accelerate the reaction efficiency, and thus improve the formaldehyde removal efficiency. At the same time, the guide strip 17 blocks the flowing water and turns its flow direction, thereby improving the combination efficiency of lime powder and wastewater.

[0040] The fixed box 91 has two protective boxes 18 fixedly installed inside, and the protective box 18 has a movably installed interceptor plate 19 inside. The two interceptor plates 19 are respectively movably snapped into the ends of the primary sedimentation tank 1 and the reaction tank 2, which can seal the top of the square hole. The protective box 18 is symmetrically fixedly installed with telescopic rods IV 20, and the extended end of the telescopic rods IV 20 is fixedly connected to the side of the interceptor plate 19. The interceptor plate 19 can be pushed and pulled by the telescopic rods IV 20, thereby opening and closing the square hole. When it is necessary to transport the sediment to the transfer box 62, the interceptor plate 62 can be pulled open. When the reaction is in the reaction tank 2, the interceptor plate 62 can intercept the wastewater in the tank to prevent leakage from the square hole into the gap between the reaction tank 2 and the rotating bottom plate 61. Similarly, when the sediment is pressed into the transfer box 62 by the square filter plate 74, the interceptor plate 19 extends out, pushes against the limit frame 72, and also seals the square hole to prevent a large amount of wastewater from leaking out.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-stage treatment system for formaldehyde-containing wastewater, comprising a primary sedimentation tank (1) and a reaction tank (2) placed in parallel, wherein square holes are provided at the bottom of both ends of the primary sedimentation tank (1) and the reaction tank (2), characterized in that: Also includes: The heating plate (3) is inclined between the primary sedimentation tank (1) and the reaction tank (2). It can heat the water overflowing from the primary sedimentation tank (1) and guide it into the reaction tank (2). The primary sedimentation tank (1) is provided with an overflow port (4) on the front side and an inlet (5) is provided on the rear side of the reaction tank (2). Wastewater flows out from the overflow port (4), passes through the heating plate (3), and then flows into the reaction tank (2) from the inlet (5). The transfer device (6) is movably installed at the ends of the primary sedimentation tank (1) and the heating plate (3). By rotating, it can guide the excess lime mixture inside the reaction tank (2) to the bottom of the square hole of the primary sedimentation tank (1) for reuse, and discharge the sedimented waste in the primary sedimentation tank (1). The transfer device (6) includes a rotating base plate (61) and a rotating motor (64). The rotating motor (64) is located at the bottom center of the rotating base plate (61), and its rotating shaft is fixedly connected to the rotating base plate (61). Transfer boxes (62) that fit the square holes are evenly fixed on the rotating base plate (61), and a three-way solenoid valve (63) is provided at one end of the transfer box (62). The transfer box (62) has two cavities inside, and the middle partition is provided with a through hole. The three-way solenoid valve (63) is connected to the lower cavity of the transfer box (62). A rack (11) is fixedly installed on the top of the primary sedimentation tank (1). The primary sedimentation tank (1) and the reaction tank (2) are equipped with filtration devices (7), and a servo motor (15) is installed at the top of one end of the filtration device (7). A drive shaft (12) is movably installed on the filtration device (7), and a traveling gear (13) that meshes with a rack (11) is fixedly installed on the drive shaft (12). A belt drive device (14) for transmission is provided between the drive shaft (12) and the servo motor (15). The filtration device (7) is equipped with a flow guide device (8), which includes a support. The support frame (81) and the connecting plate (83) are provided. Multiple guide boxes (82) are movably arranged on the support frame (81), and the guide boxes (82) are connected in series through the connecting plate (83). A connecting rod (84) is movably arranged on the top of the connecting plate (83). A telescopic rod III (85) is movably arranged on the top of the support frame (81), and the extended end of the telescopic rod III (85) is movably connected to the connecting rod (84). The telescopic rod III (85) drives the guide box (82) to deflect in direction. An impeller (86) is movably arranged inside the guide box (82).

2. The multi-stage treatment system for formaldehyde-containing wastewater according to claim 1, characterized in that: The filtration device (7) includes a T-shaped frame (71), with limit frames (72) movably arranged on both sides of the T-shaped frame (71). A filter cloth (73) is arranged on the top of the limit frame (72). A square filter plate (74) is movably arranged on the limit frame (72) and fixedly connected to one end of the filter cloth (73). A telescopic rod I (75) is movably arranged on the T-shaped frame (71), and the extended end of the telescopic rod I (75) is movably connected to the limit frame (72) for adjusting the angle of the limit frame (72).

3. The multi-stage treatment system for formaldehyde-containing wastewater according to claim 2, characterized in that: The limiting frame (72) includes a top limiting rod (721) and a turning rod (722). The top limiting rod (721) and the turning rod (722) are movably connected. The height of the turning rod (722) is the same as the height of the square filter plate (74) and the width of the square hole. The bottom of the T-shaped frame (71) is provided with a telescopic rod II (76). The protruding end of the top of the telescopic rod II (76) is movably connected to the top of the turning rod (722).

4. The multi-stage treatment system for formaldehyde-containing wastewater according to claim 3, characterized in that: A rotating gear (77) is fixedly installed on the rotating shaft of the filter cloth (73), and a drive motor (78) is fixedly installed on the top of the other end of the T-shaped frame (71). A transmission gear (79) that meshes with the rotating gear (77) is movably installed on the T-shaped frame (71), and a main gear that meshes with the transmission gear (79) is fixedly installed on the output shaft of the drive motor (78).

5. A multi-stage treatment system for formaldehyde-containing wastewater according to claim 1, characterized in that: End filter boxes (9) are fixedly installed at the ends of the primary sedimentation tank (1) and the reaction tank (2). The end filter box (9) includes a fixed box (91). A receiving plate (92) is fixedly installed on the top of the fixed box (91), and one end of the receiving plate (92) is connected to one end of the primary sedimentation tank (1). A spiral filter plate (93) is fixedly installed in the middle of the fixed box (91). A connecting pipe (94) is fixedly installed on the spiral filter plate (93) that penetrates the bottom of the fixed box (91). Wastewater on the receiving plate (92) can be guided to the transfer box (62) below for rinsing.

6. The multi-stage treatment system for formaldehyde-containing wastewater according to claim 1, characterized in that: A dust collection box (10) is fixedly installed on the filter device (7) and above the heating plate (3), and a drive shaft (12) passes through the dust collection box (10). A contact rod (16) that can abut against the bottom of the inner cavity of the dust collection box (10) is fixedly installed on the drive shaft (12). A guide strip (17) is uniformly fixedly installed on the upper surface of the heating plate (3).

7. A multi-stage treatment system for formaldehyde-containing wastewater according to claim 5, characterized in that: The fixed box (91) is equipped with two protective boxes (18) inside, and the protective box (18) is equipped with a movable interceptor plate (19). The two interceptor plates (19) are respectively movably connected to the ends of the primary sedimentation tank (1) and the reaction tank (2), and can be closed above the square hole. The protective box (18) is symmetrically fixed with telescopic rods IV (20), and the extended end of the telescopic rods IV (20) is fixedly connected to the side of the interceptor plate (19).

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